The present invention relates to methods of processing video signals and particularly, but not exclusively, to the processing of material originating from either 625 line 50Hz video or film camera in order to produce recorded media such as compact discs in different formats which can be played and displayed on either PAL or NTSC television equipment.
An example of a processing system for obtaining video images from stock using both high- and standard-definition telecine apparatus is given in European Patent Application EP-A-0595323 (Fujinami et al/Sony). The high-definition telecine is used to enable the production of a video signal with increased vertical resolution such as to be capable of display on a progressive scanning display. By a further process reducing the number of pixels, a standard-definition progressive scan signal is produced from which a standard-definition interlaced signal is generated.
A principal use for such systems is in the production of NTSC standard videos, optical discs, or other recorded media. According to conventional techniques, this requires a standards conversion process to produce a 525 line NTSC video tape from which the discs can be prepared. The cost of preparing the standards converted tape is typically in the region of US$15,000 for the material for one complete disc. One use for the system outlined above is in the conversion of music videos (which are often produced on film) to compact disc (CD) standards.
The problems of the differing requirements of the PAL and NTSC systems have long been recognised. Attempts to overcome them have included display systems with in-built standards conversion facilities as described in, for example, EP-A-0639029 (Lee/Goldstar) and U.S. Pat. No 5,280,351 (Wilkinson/Sony UK). Such options are presently unattractive, however, due to the high increased cost of the sets, which cost must be borne by the customer.